Appeal No. 2006-1218
Application No. 10/601,884
period of 30 minutes to 3 hours (column 3, lines 40-43). It is
the Examiner’s finding that the LiF sintering aid is removed
from Sellers’ product during this second stage. In support of
his finding, the Examiner relies upon Appellants’ admission in
the response filed January 7, 2005 that a temperature of 1550°C
is “too high for the sintering aid to remain in the product.”
This finding is also supported by the fact that Sellers’
heating schedule falls entirely within that disclosed in the
Appellants’ specification. On page 11 of the specification the
following temperature schedule is employed:
1. temperature is increased from ambient to 950°C and held
there for 30 minutes to melt the LiF sintering aid,
2. temperature is increased from 950°C to 1200°C and held
for 30 minutes to allow the vaporized LiF to leave the product,
and
3. temperature is increased from 1200°C to 1550°C and held
for 2 hours to fully densify the product.
As is clearly indicated by Appellants’ disclosure, when spinel
is heated to a temperature of 1200°C, the LiF sintering aid is
vaporized and removed from the product. Sellers heats his
product to a temperature higher than 1200°C (i.e. 1300°C to
1600°C). Moreover, Appellants teach that the 1200°C temperature
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